The use of rocket engines to accelerate ramjet-powered vehicles is well known. In addition to detachable rocket boosters, the prior art includes integral rocket-ramjet configurations typically formed by a tandem arrangement of the ramjet-rocket engines wherein the rocket engine provides the initial acceleration and the ramjet provides the cruise power.
After the acceleration phase, the rocket engine is jettisoned. Another variation provides the rocket grain within the ramjet combustor typically jettisoning only the rocket nozzle. Despite the weight and space savings, limitations remain. Various inlet opening and closing mechanisms are required in addition to the exhaust nozzle mechanism and jettisoning hardware. A more complete background of the development field, incorporated herein by reference is included in John Hopkins Applied Physics Laboratory Technical Digest, Volume 13, Number 1 (1992), and covers generally six areas:
1. Talos: A liquid-fueled ramjet missile that recorded a total of 1,349 flights, of which 750 successive flights were without a ramjet engine failure. Later, as a supersonic target (Vandal), 320 missiles were flown with a success record of 98%. PA0 2. Typhon Long-Range (LR): A smaller, higher-speed, liquid-fueled ramjet similar in design to Talos that had eight successful ramjet flight demonstrations without an engine failure. PA0 3. Augmented Thrust Propulsion (ATP): A ducted rocket using a boron-based solid fuel. PA0 4. Supersonic Combustion Ramjet Missile (SCRAM): A hypersonic vehicle design based on the use of liquid borane high-energy fuels (HEF). PA0 5. Dual-Combustor Ramjet (DCR): A hypersonic vehicle design using a hybrid ramjet/scramjet engine that operates with liquid hydrocarbon fuels, which are more logistically acceptable that HEF. PA0 6. Advanced Surface-to-Air Ramjet (ASAR): An integral-rocket ramjet that uses the empty solid-rocket booster chamber as a dump-type ramjet combustion chamber and uses liquid hydrocarbon fuels.
All of the above provide a general background, however the specific background area for the present invention is the combination of Nos. 3 and 5, Augmented Thrust Propulsion and the Dual-Combustor Ramjet.